According to the world Health Organization's August 2014 update on visual impairment and blindness, uncorrected refractive errors are the main cause for moderate and severe visual impairment in the world and 80% percent of all visual impairment can be prevented or cured. Even within the U.S., many people lack the funds, insurance, or time needed for a traditional office-based refraction with an eye care professional.
Uncorrected refractive error results in loss of productivity and quality of life. More recently, objective refraction techniques have become common in the field. Objective refraction techniques attempt to correct for refractive error without a response from the user or patient. Types of objective refraction comprise: retinoscopy, auto-refractors, and wavefront aberrometers. These methods have advantages and disadvantages. A well-known problem with wavefront aberometers is that more negative diopters may be added to a prescription than is necessary causing device myopia, a condition commonly known to those skilled in the art. Retinoscopy may require a highly skilled and trained eye care professional to measure refractive error using a lens set and reflective technique but is typically not accurate enough to find the best vision. Auto-refraction, wavefront sensing and refractometers may require two people, including an eye care professional to provide instructions, read device output and troubleshoot results. They may also require sophisticated and costly equipment which places these techniques out of reach for lower income or underinsured consumers. Further, many of these devices, including auto-refractors are currently not far enough advanced to determine best vision. They are often used by eye care professionals to screen vision prior to engaging in subjective refraction, or as another benchmarking method prior to conducting surgical techniques for vision correction. When these methods are more advanced, they may replace traditional subjective methods; however, their current limitations as discussed above, are widely understood in the field and cannot find a user's preferred vision.
For years, eye care professionals have been providing patients with subjective refraction in an office based setting to correct for the above types of refractive error conditions by manipulating trial lenses by means of well-known manual and automated/motorized devices such as the phoroptor, combined with the Jackson-Cross Cylinder. Automated phoroptors are commonly used in office-based settings. It is common knowledge to those skilled in the art that these gold standard methods are the most accurate means for measuring refractive error. However, existing subjective methods may require an expert to operate or may require evaluation from an eye care professional, thus potentially impeding the possibility of a user/customer operated system.
In light of the above it would be desirable to provide an auto-phoropter system that allows a user to perform subjective self-refraction with low cost, flexibility and data access.